Clarification around gmail history api and mailbox full sync

Question

How often does the historyId change, it says in the doc that in some cases it might be valid only for few hours, how frequent is that?

And In case I get a 404 in history api then can I rely on updating the historyId to the latest historyId for new changes via pub/sub and instead of doing a full sync, I use query parameter to fetch messages whose timestamp is greater than the max timestamp I had in my database to reduce resource consumption?

Answer 1

The response to your question as per documentation:

A historyId is typically valid for at least a week, but in some rare circumstances may be valid for only a few hours.

If you receive an HTTP 404 error response, your application should perform a full sync.